The ACB-728 Annunciator Control Board is capable of controlling 128 inputs on the AIB-716 Annunciator Input Board and/or 128 outputs on the AOB716 Annunciator Output Board & ARB716 Annunciator Relay Board. The AIB716 provides 16 inputs while the AOB716 provides 16 Open Collector outputs and the ARB-716 provides 16 Form ‘C’ Dry Contact outputs. The ACB-728 has inputs for SYSTEM RESET, ALARM/TROUBLE ACKNOWLEDGE, ALARM SILENCE, LAMP TEST, and four user-defined SPARE INPUTS. All inputs require normally open switches. Two outputs are also supplied by the Annunciator Control Board for an Alarm LED and Piezo. A seven-segment diagnostic LED is used for troubleshooting.